Badalabad Shear Zone Structures Study at North Khoy

The area of study is located in the north of Khoy and north west Iran and mainly consists of gneiss, gneissic amphibolites, mylonitic gabbro, diorite mylonitic and mylonitic granite affected by the shear zone form brittle – ductile and ductile deformation. Structural and microstructural study display reverse and strike slip shear zone. Three generations of deformation have been identified in KMC (D1-D3). The D1/D2 deformation is defined by isoclinals folds and S1 and S2 foliations indicate NE-SW (σ1) regional shortening that the deformation condition is ductile. The sense of movement of this generation is dextral. Folds belonging to D3 are generally open to tight asymmetrical and overprint the mylonite foliation. The brittle deformation condition at K-feldspar porphyroclasts and the ductile deformation condition at QR porphyroclasts also indicate a dextral sense of shear that indicates NW-SE (σ1) regional shortening. The deformation condition is near the brittle-ductile transition. Dextral transpression associated with D2/D3 is responsible for the formation of the shear zone. Both D1/D2 and D3 have a dextral sense of movement, and are interpreted as a continuous progressive deformation. From the tectonics point of view, the area demonstrates inclined dextral transpression. The reason for this particular tectonic regime is oblique collision of Arabian platform with west Alborz-Azerbaijan block. The resulting stress was resolved into orthogonal, compressional and shear components. The compressional stress has caused the folding and thrusting whereas the shear stress produced the dextral strike-slip component of Khoy shear zone (KSZ).